[InterNetNews/inn] 425f1a: Fix build with LibreSSL

[Julien ÉLIE]

  Branch: refs/heads/2.6
  Home:   https://github.com/InterNetNews/inn
  Commit: 425f1a8ab3205fa7ded8bc98e14775d09c25e4dd
      https://github.com/InterNetNews/inn/commit/425f1a8ab3205fa7ded8bc98e14775d09c25e4dd
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2022-01-22 (Sat, 22 Jan 2022)

  Changed paths:
    M nnrpd/tls.c

  Log Message:
  -----------
  Fix build with LibreSSL

LibreSSL is not API-compatible with OpenSSL versions > 1.0.1.
So we just do not use new OpenSSL APIs with it.